How to align the camera in a solved motion tracked scene?
When doing motion tracking you can set the origin of the scene on the Solve Tab's Orientation. Select a marker you want and press on Set Origin.



When you setup the tracking scene that particular tracker will be placed at the origin of your 3D scene. (to make the trackers into empties press on Link Empty to Track)



Those empties will be visible if you enable the Motion tracking box on the 3D view.



All of the tracking information is linked to the camera, so can move the camera and the empties will follow, or you can select any of the empties and move it where you want and the rest will follow as well.

To rotate the camera around a particular point. Select an emtpy, press ShiftS and select cursor to selected. Then set your Pivot Point to 3D cursor.